[PATCH 2/2] ntdll: Prevent Find{Set, Clear}Run from reading past the end of bitmap

From: Michał Janiszewski

This can be happen in sample arrays (hex):
FindSetRun:   00 00 00 00 00 00 00 ff
FindClearRun: ff ff ff ff ff ff ff 00

Such arrays were added in previous commit to tests and should now be
fixed.

Signed-off-by: Michał Janiszewski 
---
 dlls/ntdll/rtlbitmap.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/dlls/ntdll/rtlbitmap.c b/dlls/ntdll/rtlbitmap.c
index 20108f5035..d0a4e5cf28 100644
--- a/dlls/ntdll/rtlbitmap.c
+++ b/dlls/ntdll/rtlbitmap.c
@@ -731,6 +731,12 @@ static ULONG NTDLL_FindSetRun(PCRTL_BITMAP lpBits, ULONG ulStart, PULONG lpSize)
       return ~0U;
   }

+  /* Check if reached the end of bitmap */
+  if (ulStart >= lpBits->SizeOfBitMap) {
+    *lpSize = ulCount - (ulStart - lpBits->SizeOfBitMap);
+    return ulFoundAt;
+  }
+
   /* Count blocks of 8 set bits */
   while (*lpOut == 0xff)
   {
@@ -822,6 +828,12 @@ static ULONG NTDLL_FindClearRun(PCRTL_BITMAP lpBits, ULONG ulStart, PULONG lpSiz
       return ~0U;
   }

+  /* Check if reached the end of bitmap */
+  if (ulStart >= lpBits->SizeOfBitMap) {
+    *lpSize = ulCount - (ulStart - lpBits->SizeOfBitMap);
+    return ulFoundAt;
+  }
+
   /* Count blocks of 8 clear bits */
   while (!*lpOut)
   {